1. Field of the Invention
The present invention relates to an adaptive optical apparatus and an imaging apparatus having the adaptive optical apparatus.
2. Description of the Related Art
An optical coherence tomography (OCT) using multi-wavelength light wave interference is a method for acquiring a tomographic image of a sample, in particular, of a fundus, with a high resolution.
Hereinafter, an optical tomographic imaging apparatus for capturing an optical tomographic image with such an OCT is referred to as an OCT apparatus.
In recent years, the increased beam diameter of a measuring beam in a Fourier domain OCT apparatus has allowed acquiring the tomographic image of a retina with a high transverse resolution.
Along with the increase of the beam diameter of a measuring beam, the problem has arisen that the SN ratio and the resolution of a tomographic image are lowered due to aberration caused by the distortion of a curved surface and the ununiformity of a refractive index in a subject's eye when the tomographic image of a retina is acquired.
To solve the problem, an adaptive optical OCT apparatus with an adaptive optical system for measuring the aberration of a subject's eye with a wavefront sensor in real time to compensate for the aberration with a wavefront correction device has been developed to enable acquiring a tomographic image with a high transverse resolution.
Japanese Patent Application Laid-Open No. 2007-14569 discusses an ophthalmological photographing apparatus, as an apparatus using such an adaptive optical system, capable of acquiring a fundus image using an adaptive optical and a liquid crystal spatial phase modulator, a polygon mirror, and a galvanometer mirror in a scanning laser ophthalmoscope (SLO).
The ophthalmological photographing apparatus corrects the aberration caused in the subject's eye using the liquid crystal spatial phase modulator to avoid the deterioration of transverse resolution. A generally narrow-band semiconductor laser is used as a light source. Nothing has been written about the use of a wide-band light source in the OCT apparatus.
The above liquid crystal spatial phase modulator modulates a refractive index using the birefringence of a liquid crystal, so that the amount of modulation depends upon a wavelength. For this reason, if the OCT apparatus is formed using a wide-band light source, an improvement is required to acquire a high-resolution image.
If aberration is corrected using a phase wrapping technique, the influence becomes more prominent.